Validation of a single point flow cytometric assay for determining P-glycoprotein activity in multidrug resistant cell lines
Bibliographic record
Abstract
P-glycoprotein, a transmembrane protein which acts as an energy dependent efflux pump, has been implicated as one mechanism of multidrug resistance (MDR) in human tumours. Commonly employed assays measure P-glycoprotein immunohistochemically or mdr1 messenger RNA. In this study we compared a single point flow cytometric assay for determining activity of P-glycoprotein with cellular expression of P-glycoprotein determined by Western blot. Five cell lines, with varying levels of multiple drug resistance, were incubated with daunorubicin (DNR) in the presence (treated) and absence (control) of cyclosporine or verapamil, agents known to inhibit the activity of P-glycoprotein. The treated cell lines, along with non-treated controls were examined for intracellular concentrations of DNR measured by fluorescence intensity using a flow cytometer. The ratio of fluorescence intensity expressed in the treated/control was used as an index of functional activity of P-glycoprotein. Functional activity of the P-glycoprotein as determined by flow cytometry correlates highly with cellular content of P-glycoprotein measured by western blot (correlation coefficients of r = 0.90-0.98 for the various cell line combinations). This method represents a rapid single point flow cytometric assay which may be suitable for screening clinical samples for P-glycoprotein activity.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".